Rethink Carbon is building digital infrastructure to support the UK’s voluntary carbon market, helping organisations manage and scale nature-based climate projects more effectively. Founded by Zoe Russell and Mark Caulfield, the company combines deep expertise in ecology, land management, and software development to tackle one of the biggest long-term challenges in climate action: how to support trustworthy, scalable carbon projects through better technology.
Working across woodland creation and peatland restoration, Rethink Carbon is developing tools that simplify project management, improve transparency, and help accelerate climate-focused land use decisions.
Combining ecology and software expertise
Rethink Carbon’s origins sit at the intersection of two very different backgrounds.
Before becoming a founder, Zoe Russell spent years working in ecology, conservation and the public sector. After studying zoology and completing a PhD focused on red grouse populations in the Scottish Highlands, she worked for NatureScot for more than 16 years across land management, protected areas and environmental planning.
A later move into software project management unexpectedly shifted the direction of her career.
“I don’t know anything about software, but I’m sure I can manage a project,” Zoe says, reflecting on the role that first introduced her to digital product development.
While managing software development projects at NatureScot, Zoe met her future co-founder Mark, a software engineer and technical specialist who had been contracted to build systems for the organisation.
The two later founded software company Ginger together before eventually launching Rethink Carbon through the Scottish Government-backed CivTech programme.
“We’d always kept an eye on CivTech challenges,” Zoe explains. “Then one came up around using technology to help land managers make better land use decisions and we thought - wait a minute - that combines both of our backgrounds.”
That challenge ultimately became the foundation for Rethink Carbon.
Supporting climate action through technology
Initially, Rethink Carbon focused on helping land managers make informed decisions around land use and climate-focused projects.
More recently, the company’s work has evolved into supporting the wider voluntary carbon market in the UK - particularly around woodland and peatland carbon projects.
“In the UK, the two major nature-based approaches are planting trees and restoring peatland,” Zoe explains. “Scotland alone has huge peatland carbon storage potential.”
Through a second CivTech challenge, Rethink Carbon began developing infrastructure to support the Woodland Carbon Code and Peatland Code - frameworks used to validate and manage carbon projects across the UK.
The challenge focused on improving transparency, increasing trust for investors, and streamlining how projects move through the system.
To support this, Rethink Carbon is now building a platform designed to make the process more efficient for project developers and organisations operating within the carbon market.
The company’s customers are typically environmental consultants and project developers - organisations responsible for designing, managing and delivering large-scale woodland and peatland projects on behalf of landowners.
Navigating the realities of an early-stage startup
Like many early-stage startups, Rethink Carbon's journey has involved navigating uncertainty, funding pressures and evolving markets. One of the biggest challenges has been validating demand in a highly specialised sector. Nature markets were expected to scale fast. Five years on, they still haven't fully taken off and working out who the real customer was, and whether they were ready, took longer than anticipated.
The complexity of the market created its own adoption challenges too. Environmental consultants already had established ways of working, and switching to a new platform isn't a straightforward sell. That slower adoption cycle has knock-on effects: without revenue to reinvest, the team has had to balance client project work with building their own product, always conscious of the line between running a consultancy and building a software company.
The founder journey brought its own adjustment. For a long time, Zoe struggled to see herself as a founder at all.
"We wouldn't have got where we are if it wasn't for the two of us," Zoe says now, a recognition that came gradually, and matters.
Expanding global perspective through Techscaler
As Rethink Carbon continued to grow, Techscaler's international programmes helped the company look beyond the UK market. In 2025, Zoe joined the Singapore programme, focused on connecting Scottish startups with Southeast Asia's innovation ecosystem, timing that aligned closely with Rethink Carbon's growing focus on international carbon infrastructure.
Zoe spent significant time preparing before she travelled, researching carbon standards, mapping organisations and reaching out directly to people working in the sector. That groundwork paid off. The conversations that followed revealed a carbon market operating at a completely different scale; where peatland projects in Indonesia routinely exceed 5,000 hectares, compared to the 20 to 100-hectare projects typical in the UK.
What struck her as much as the scale was the openness. "In Singapore, people were incredibly open about the challenges, the opportunities and how things actually work," she says, a contrast with the more guarded approach she'd encountered closer to home. Those conversations broadened the company's thinking around partnerships and long-term opportunity in ways that a full calendar of day-to-day delivery rarely allows.
Building towards the next stage
Rethink Carbon is currently preparing to launch its new platform - currently titled Rethink Codes - later this year.
The platform is designed to support the UK’s voluntary carbon market by improving how projects are managed, assessed and monitored.
Launching the platform marks a major milestone for the company and the next phase of its growth.
At the same time, the team continues to explore new opportunities and partnerships emerging from the Singapore programme.
“I think it’s about staying flexible,” Zoe says. “You say yes to opportunities because one out of ten might turn into something important.”
That mindset - combining deep sector expertise with adaptability - continues to shape Rethink Carbon’s approach as the company grows.
Growth and Milestones Highlights
Rethink Carbon has reached several key milestones:
- Formation of Rethink Carbon through the CivTech programme
- Development of digital tools supporting nature-based climate projects
- Participation in multiple CivTech challenges and accelerator programmes
- Selection for Techscaler’s Singapore programme
- Expansion into infrastructure supporting the UK voluntary carbon market
- Development of the upcoming Rethink Codes platform
- Ongoing international partnership and market exploration
Rethink Carbon reflects a growing movement of climate-focused startups using technology to support large-scale environmental change.
By combining expertise in ecology, land management and software development, the company is helping modernise systems that sit at the centre of climate action and carbon reduction efforts. Through programmes like CivTech and Techscaler, that work is continuing to scale - from Scotland to international markets.
Get involved
Techscaler supports startups across Scotland through education, community and international market access programmes designed to help founders build and scale ambitious businesses.
Click here to find out more about Techscaler and upcoming programmes.
.png)
